platform_system_vold/Volume.cpp

/*
 * Copyright (C) 2008 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include <stdlib.h>
#include <string.h>
#include <dirent.h>
#include <errno.h>
#include <fcntl.h>

#include <sys/types.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/mman.h>
#include <sys/mount.h>

#include <linux/kdev_t.h>

#include <cutils/properties.h>

#include "diskmbr.h"

#define LOG_TAG "Vold"

#include <cutils/log.h>

#include "Volume.h"
#include "VolumeManager.h"
#include "ResponseCode.h"
#include "Fat.h"
#include "Process.h"

extern "C" void dos_partition_dec(void const *pp, struct dos_partition *d);
extern "C" void dos_partition_enc(void *pp, struct dos_partition *d);


/*
 * Secure directory - stuff that only root can see
 */
const char *Volume::SECDIR            = "/mnt/secure";

/*
 * Secure staging directory - where media is mounted for preparation
 */
const char *Volume::SEC_STGDIR        = "/mnt/secure/staging";

/*
 * Path to the directory on the media which contains publicly accessable
 * asec imagefiles. This path will be obscured before the mount is
 * exposed to non priviledged users.
 */
const char *Volume::SEC_STG_SECIMGDIR = "/mnt/secure/staging/.android_secure";

/*
 * Path to where *only* root can access asec imagefiles
 */
const char *Volume::SEC_ASECDIR       = "/mnt/secure/asec";

/*
 * Path to where secure containers are mounted
 */
const char *Volume::ASECDIR           = "/mnt/asec";

static const char *stateToStr(int state) {
    if (state == Volume::State_Init)
        return "Initializing";
    else if (state == Volume::State_NoMedia)
        return "No-Media";
    else if (state == Volume::State_Idle)
        return "Idle-Unmounted";
    else if (state == Volume::State_Pending)
        return "Pending";
    else if (state == Volume::State_Mounted)
        return "Mounted";
    else if (state == Volume::State_Unmounting)
        return "Unmounting";
    else if (state == Volume::State_Checking)
        return "Checking";
    else if (state == Volume::State_Formatting)
        return "Formatting";
    else if (state == Volume::State_Shared)
        return "Shared-Unmounted";
    else if (state == Volume::State_SharedMnt)
        return "Shared-Mounted";
    else
        return "Unknown-Error";
}

Volume::Volume(VolumeManager *vm, const char *label, const char *mount_point) {
    mVm = vm;
    mLabel = strdup(label);
    mMountpoint = strdup(mount_point);
    mState = Volume::State_Init;
    mCurrentlyMountedKdev = -1;
}

Volume::~Volume() {
    free(mLabel);
    free(mMountpoint);
}

dev_t Volume::getDiskDevice() {
    return MKDEV(0, 0);
};

void Volume::handleVolumeShared() {
}

void Volume::handleVolumeUnshared() {
}

int Volume::handleBlockEvent(NetlinkEvent *evt) {
    errno = ENOSYS;
    return -1;
}

void Volume::setState(int state) {
    char msg[255];
    int oldState = mState;

    if (oldState == state) {
        LOGW("Duplicate state (%d)\n", state);
        return;
    }

    mState = state;

    LOGD("Volume %s state changing %d (%s) -> %d (%s)", mLabel,
         oldState, stateToStr(oldState), mState, stateToStr(mState));
    snprintf(msg, sizeof(msg),
             "Volume %s %s state changed from %d (%s) to %d (%s)", getLabel(),
             getMountpoint(), oldState, stateToStr(oldState), mState,
             stateToStr(mState));

    mVm->getBroadcaster()->sendBroadcast(ResponseCode::VolumeStateChange,
                                         msg, false);
}

int Volume::createDeviceNode(const char *path, int major, int minor) {
    mode_t mode = 0660 | S_IFBLK;
    dev_t dev = (major << 8) | minor;
    if (mknod(path, mode, dev) < 0) {
        if (errno != EEXIST) {
            return -1;
        }
    }
    return 0;
}

int Volume::formatVol() {

    if (getState() == Volume::State_NoMedia) {
        errno = ENODEV;
        return -1;
    } else if (getState() != Volume::State_Idle) {
        errno = EBUSY;
        return -1;
    }

    if (isMountpointMounted(getMountpoint())) {
        LOGW("Volume is idle but appears to be mounted - fixing");
        setState(Volume::State_Mounted);
        // mCurrentlyMountedKdev = XXX
        errno = EBUSY;
        return -1;
    }

    char devicePath[255];
    dev_t diskNode = getDiskDevice();
    dev_t partNode = MKDEV(MAJOR(diskNode), 1); // XXX: Hmmm

    sprintf(devicePath, "/dev/block/vold/%d:%d",
            MAJOR(diskNode), MINOR(diskNode));

    LOGI("Formatting volume %s (%s)", getLabel(), devicePath);

    if (initializeMbr(devicePath)) {
        LOGE("Failed to initialize MBR (%s)", strerror(errno));
        goto err;
    }

    sprintf(devicePath, "/dev/block/vold/%d:%d",
            MAJOR(partNode), MINOR(partNode));

    if (Fat::format(devicePath, 0)) {
        LOGE("Failed to format (%s)", strerror(errno));
        goto err;
    }

    return 0;
err:
    return -1;
}

bool Volume::isMountpointMounted(const char *path) {
    char device[256];
    char mount_path[256];
    char rest[256];
    FILE *fp;
    char line[1024];

    if (!(fp = fopen("/proc/mounts", "r"))) {
        LOGE("Error opening /proc/mounts (%s)", strerror(errno));
        return false;
    }

    while(fgets(line, sizeof(line), fp)) {
        line[strlen(line)-1] = '\0';
        sscanf(line, "%255s %255s %255s\n", device, mount_path, rest);
        if (!strcmp(mount_path, path)) {
            fclose(fp);
            return true;
        }

    }

    fclose(fp);
    return false;
}

int Volume::mountVol() {
    dev_t deviceNodes[4];
    int n, i, rc = 0;
    char errmsg[255];

    if (getState() == Volume::State_NoMedia) {
        snprintf(errmsg, sizeof(errmsg),
                 "Volume %s %s mount failed - no media",
                 getLabel(), getMountpoint());
        mVm->getBroadcaster()->sendBroadcast(
                                         ResponseCode::VolumeMountFailedNoMedia,
                                         errmsg, false);
        errno = ENODEV;
        return -1;
    } else if (getState() != Volume::State_Idle) {
        errno = EBUSY;
        return -1;
    }

    if (isMountpointMounted(getMountpoint())) {
        LOGW("Volume is idle but appears to be mounted - fixing");
        setState(Volume::State_Mounted);
        // mCurrentlyMountedKdev = XXX
        return 0;
    }

    n = getDeviceNodes((dev_t *) &deviceNodes, 4);
    if (!n) {
        LOGE("Failed to get device nodes (%s)\n", strerror(errno));
        return -1;
    }

    for (i = 0; i < n; i++) {
        char devicePath[255];

        sprintf(devicePath, "/dev/block/vold/%d:%d", MAJOR(deviceNodes[i]),
                MINOR(deviceNodes[i]));

        LOGI("%s being considered for volume %s\n", devicePath, getLabel());

        errno = 0;
        setState(Volume::State_Checking);

        if (Fat::check(devicePath)) {
            if (errno == ENODATA) {
                LOGW("%s does not contain a FAT filesystem\n", devicePath);
                continue;
            }
            errno = EIO;
            /* Badness - abort the mount */
            LOGE("%s failed FS checks (%s)", devicePath, strerror(errno));
            setState(Volume::State_Idle);
            return -1;
        }

        /*
         * Mount the device on our internal staging mountpoint so we can
         * muck with it before exposing it to non priviledged users.
         */
        errno = 0;
        if (Fat::doMount(devicePath, "/mnt/secure/staging", false, false, 1000, 1015, 0702, true)) {
            LOGE("%s failed to mount via VFAT (%s)\n", devicePath, strerror(errno));
            continue;
        }

        LOGI("Device %s, target %s mounted @ /mnt/secure/staging", devicePath, getMountpoint());

        if (createBindMounts()) {
            LOGE("Failed to create bindmounts (%s)", strerror(errno));
            umount("/mnt/secure/staging");
            setState(Volume::State_Idle);
            return -1;
        }

        /*
         * Now that the bindmount trickery is done, atomically move the
         * whole subtree to expose it to non priviledged users.
         */
        if (doMoveMount("/mnt/secure/staging", getMountpoint(), false)) {
            LOGE("Failed to move mount (%s)", strerror(errno));
            umount("/mnt/secure/staging");
            setState(Volume::State_Idle);
            return -1;
        }
        setState(Volume::State_Mounted);
        mCurrentlyMountedKdev = deviceNodes[i];
        return 0;
    }

    LOGE("Volume %s found no suitable devices for mounting :(\n", getLabel());
    setState(Volume::State_Idle);

    return -1;
}

int Volume::createBindMounts() {
    unsigned long flags;

    /*
     * Rename old /android_secure -> /.android_secure
     */
    if (!access("/mnt/secure/staging/android_secure", R_OK | X_OK) &&
         access(SEC_STG_SECIMGDIR, R_OK | X_OK)) {
        if (rename("/mnt/secure/staging/android_secure", SEC_STG_SECIMGDIR)) {
            LOGE("Failed to rename legacy asec dir (%s)", strerror(errno));
        }
    }

    /*
     * Ensure that /android_secure exists and is a directory
     */
    if (access(SEC_STG_SECIMGDIR, R_OK | X_OK)) {
        if (errno == ENOENT) {
            if (mkdir(SEC_STG_SECIMGDIR, 0777)) {
                LOGE("Failed to create %s (%s)", SEC_STG_SECIMGDIR, strerror(errno));
                return -1;
            }
        } else {
            LOGE("Failed to access %s (%s)", SEC_STG_SECIMGDIR, strerror(errno));
            return -1;
        }
    } else {
        struct stat sbuf;

        if (stat(SEC_STG_SECIMGDIR, &sbuf)) {
            LOGE("Failed to stat %s (%s)", SEC_STG_SECIMGDIR, strerror(errno));
            return -1;
        }
        if (!S_ISDIR(sbuf.st_mode)) {
            LOGE("%s is not a directory", SEC_STG_SECIMGDIR);
            errno = ENOTDIR;
            return -1;
        }
    }

    /*
     * Bind mount /mnt/secure/staging/android_secure -> /mnt/secure/asec so we'll
     * have a root only accessable mountpoint for it.
     */
    if (mount(SEC_STG_SECIMGDIR, SEC_ASECDIR, "", MS_BIND, NULL)) {
        LOGE("Failed to bind mount points %s -> %s (%s)",
                SEC_STG_SECIMGDIR, SEC_ASECDIR, strerror(errno));
        return -1;
    }

    /*
     * Mount a read-only, zero-sized tmpfs  on <mountpoint>/android_secure to
     * obscure the underlying directory from everybody - sneaky eh? ;)
     */
    if (mount("tmpfs", SEC_STG_SECIMGDIR, "tmpfs", MS_RDONLY, "size=0,mode=000,uid=0,gid=0")) {
        LOGE("Failed to obscure %s (%s)", SEC_STG_SECIMGDIR, strerror(errno));
        umount("/mnt/asec_secure");
        return -1;
    }

    return 0;
}

int Volume::doMoveMount(const char *src, const char *dst, bool force) {
    unsigned int flags = MS_MOVE;
    int retries = 5;

    while(retries--) {
        if (!mount(src, dst, "", flags, NULL)) {
            LOGD("Moved mount %s -> %s sucessfully", src, dst);
            return 0;
        } else if (errno != EBUSY) {
            LOGE("Failed to move mount %s -> %s (%s)", src, dst, strerror(errno));
            return -1;
        }
        int action = 0;

        if (force) {
            if (retries == 1) {
                action = 2; // SIGKILL
            } else if (retries == 2) {
                action = 1; // SIGHUP
            }
        }
        LOGW("Failed to move %s -> %s (%s, retries %d, action %d)",
                src, dst, strerror(errno), retries, action);
        Process::killProcessesWithOpenFiles(src, action);
        usleep(1000*250);
    }

    errno = EBUSY;
    LOGE("Giving up on move %s -> %s (%s)", src, dst, strerror(errno));
    return -1;
}

int Volume::doUnmount(const char *path, bool force) {
    int retries = 10;

    while (retries--) {
        if (!umount(path) || errno == EINVAL || errno == ENOENT) {
            LOGI("%s sucessfully unmounted", path);
            return 0;
        }

        int action = 0;

        if (force) {
            if (retries == 1) {
                action = 2; // SIGKILL
            } else if (retries == 2) {
                action = 1; // SIGHUP
            }
        }

        LOGW("Failed to unmount %s (%s, retries %d, action %d)",
                path, strerror(errno), retries, action);

        Process::killProcessesWithOpenFiles(path, action);
        usleep(1000*1000);
    }
    errno = EBUSY;
    LOGE("Giving up on unmount %s (%s)", path, strerror(errno));
    return -1;
}

int Volume::unmountVol(bool force) {
    int i, rc;

    if (getState() != Volume::State_Mounted) {
        LOGE("Volume %s unmount request when not mounted", getLabel());
        errno = EINVAL;
        return -1;
    }

    setState(Volume::State_Unmounting);
    usleep(1000 * 1000); // Give the framework some time to react

    /*
     * First move the mountpoint back to our internal staging point
     * so nobody else can muck with it while we work.
     */
    if (doMoveMount(getMountpoint(), SEC_STGDIR, force)) {
        LOGE("Failed to move mount %s => %s (%s)", getMountpoint(), SEC_STGDIR, strerror(errno));
        setState(Volume::State_Mounted);
        return -1;
    }

    /*
     * Unmount the tmpfs which was obscuring the asec image directory
     * from non root users
     */

    if (doUnmount(Volume::SEC_STG_SECIMGDIR, force)) {
        LOGE("Failed to unmount tmpfs on %s (%s)", SEC_STG_SECIMGDIR, strerror(errno));
        goto fail_republish;
    }

    /*
     * Remove the bindmount we were using to keep a reference to
     * the previously obscured directory.
     */

    if (doUnmount(Volume::SEC_ASECDIR, force)) {
        LOGE("Failed to remove bindmount on %s (%s)", SEC_ASECDIR, strerror(errno));
        goto fail_remount_tmpfs;
    }

    /*
     * Finally, unmount the actual block device from the staging dir
     */
    if (doUnmount(Volume::SEC_STGDIR, force)) {
        LOGE("Failed to unmount %s (%s)", SEC_STGDIR, strerror(errno));
        goto fail_recreate_bindmount;
    }

    LOGI("%s unmounted sucessfully", getMountpoint());

    setState(Volume::State_Idle);
    mCurrentlyMountedKdev = -1;
    return 0;

    /*
     * Failure handling - try to restore everything back the way it was
     */
fail_recreate_bindmount:
    if (mount(SEC_STG_SECIMGDIR, SEC_ASECDIR, "", MS_BIND, NULL)) {
        LOGE("Failed to restore bindmount after failure! - Storage will appear offline!");
        goto out_nomedia;
    }
fail_remount_tmpfs:
    if (mount("tmpfs", SEC_STG_SECIMGDIR, "tmpfs", MS_RDONLY, "size=0,mode=0,uid=0,gid=0")) {
        LOGE("Failed to restore tmpfs after failure! - Storage will appear offline!");
        goto out_nomedia;
    }
fail_republish:
    if (doMoveMount(SEC_STGDIR, getMountpoint(), force)) {
        LOGE("Failed to republish mount after failure! - Storage will appear offline!");
        goto out_nomedia;
    }

    setState(Volume::State_Mounted);
    return -1;

out_nomedia:
    setState(Volume::State_NoMedia);
    return -1;
}

int Volume::initializeMbr(const char *deviceNode) {
    int fd, rc;
    unsigned char block[512];
    struct dos_partition part;
    unsigned int nr_sec;

    if ((fd = open(deviceNode, O_RDWR)) < 0) {
        LOGE("Error opening disk file (%s)", strerror(errno));
        return -1;
    }

    if (ioctl(fd, BLKGETSIZE, &nr_sec)) {
        LOGE("Unable to get device size (%s)", strerror(errno));
        close(fd);
        return -1;
    }

    memset(&part, 0, sizeof(part));
    part.dp_flag = 0x80;
    part.dp_typ = 0xc;
    part.dp_start = ((1024 * 64) / 512) + 1;
    part.dp_size = nr_sec - part.dp_start;

    memset(block, 0, sizeof(block));
    block[0x1fe] = 0x55;
    block[0x1ff] = 0xaa;

    dos_partition_enc(block + DOSPARTOFF, &part);

    if (write(fd, block, sizeof(block)) < 0) {
        LOGE("Error writing MBR (%s)", strerror(errno));
        close(fd);
        return -1;
    }

    if (ioctl(fd, BLKRRPART, NULL) < 0) {
        LOGE("Error re-reading partition table (%s)", strerror(errno));
        close(fd);
        return -1;
    }
    close(fd);
    return 0;
}